Businesses worldwide recognize the commercial value of their data and seek reliable cost-effective ways to protect the information stored on their computer networks. A company might back up critical computing systems such as databases, file servers, web servers, and so on as part of a daily, weekly, or monthly maintenance schedule. The company may similarly protect virtual machine resources, which are becoming increasingly popular platforms for a variety of business uses. One of the perennial challenges is to protect the company's data in a way that makes efficient use of resources, while reducing the impact on productivity and network resources.